This is an operating systems lab program to implement round robin as well as priority scheduling. If you have any doubts please let me know.
#include<stdio.h>
struct process
{
char p[10];
int at,bt,pr,wt,tt,r,ar;
}a[100],temp;
int n;
void sorta()
{
int i,j;
for(i=0;i<n-1;i++)
{
for(j=0;j<n-i-1;j++)
{
if(a[j].at>a[j+1].at)
{
temp=a[j+1];
a[j+1]=a[j];
a[j]=temp;
}
}
}
}
void sortp()
{
int i,j;
for(i=0;i<n-1;i++)
{
for(j=0;j<n-i-1;j++)
{
if(a[j].pr>a[j+1].pr)
{
temp=a[j+1];
a[j+1]=a[j];
a[j]=temp;
}
}
}
}
void sortar()
{
int i,j;
for(i=0;i<n-1;i++)
{
for(j=0;j<n-i-1;j++)
{
if((a[j].ar>a[j+1].ar)||(a[j].ar==a[j+1].ar&&a[j].ar!=a[j].at))
{
temp=a[j+1];
a[j+1]=a[j];
a[j]=temp;
}
}
}
}
void main()
{
int i,c,t=0,f1=1,f=0,tq=0,cf,nt=0;
float aw=0,at=0;
printf("Enter
the number of Processes: ");
scanf("%d",&n);
printf("Enter the process
details");
for(i=0;i<n;i++)
{
printf("\nProcess
ID:");
scanf("%s",&a[i].p);
printf("\nPriority:");
scanf("%d",&a[i].pr);
printf("\nArrival
time:");
scanf("%d",&a[i].at);
printf("\nBurst
time:");
scanf("%d",&a[i].bt);
a[i].wt=a[i].tt=0;
a[i].r=a[i].bt;
a[i].ar=a[i].at;
}
printf("\nMENU:\n1.Priority\n2.Round
Robin\n");
printf("\nEnter
your choice:");
scanf("%d",&c);
switch(c)
{
case 1:
sorta();
sortp();
printf("\nGantt Chart for
Priority\n");
printf("%d",t);
while(f1==1)
{
f1=0;
for(i=0;i<n;i++)
{
if(a[i].at<=t&&a[i].r!=0)
{
a[i].wt=t-a[i].at;
aw+=a[i].wt;
printf("-----%s",a[i].p);
t=t+a[i].bt;
printf("--------");
printf("%d",t);
a[i].tt=t-a[i].at;
at+=a[i].tt;
a[i].r=0;
f=0;
f1=1;
break;
}
else
if(f==0&&a[i].r!=0)
{
nt=a[i].at;
f=f1=1;
}
else
if(nt>a[i].at&&a[i].r!=0)
nt=a[i].at;
}
if(f==1)
{
t=nt;
printf("
%d",t);
f=0;
}
}
printf("\nAverage waiting
time=%f",(aw/n));
printf("\nAverage turn around
time=%f\n",(at/n));
break;
case 2:
printf("\nEnter
the time quantum:");
scanf("%d",&tq);
if(tq>0)
{
sorta();
printf("\nGantt
Chart for Round Robin\n");
printf("%d",t);
while(f1==1)
{
cf=0;
f1=0;
sortar();
for(i=0;i<n;i++)
{
if(a[i].at<=f&&a[i].r!=0)
{
a[i].wt+=t-a[i].tt;
printf("------%s",a[i].p);
printf("------");
if(a[i].r<tq)
{
t=t+a[i].r;
a[i].r=0;
}
else
{
t=t+tq;
a[i].r-=tq;
}
printf("%d",t);
a[i].tt=a[i].ar=t;
if(cf==0)
{
cf=1;
f=t;
}
}
if(a[i].r!=0&&f1==0)
f1=1;
if(a[i].at>f)
break;
}
if(cf==0&&f1==1)
{
t=f=a[i].at;
printf(" %d",t);
}
}
for(i=0;i<n;i++)
{
a[i].wt=a[i].wt-a[i].at;
a[i].tt=a[i].tt-a[i].at;
aw+=a[i].wt;
at+=a[i].tt;
}
printf("\nAverage
waiting time=%f",(aw/n));
printf("\nAverage turn around
time=%f\n",(at/n));
}
else
printf("\nTime
quantum is wrong");
break;
default:
printf("\nWrong
Choice\n");
break;
}
}
